engleski

Radiation modified high impact polystyrene

The purpose of applying high energy (ionising)radiation with absorbed doses up to 1 MGy was to achieve controllable changes in mechanical properties of high impact polystyrene (PS-HI)and, at the same time, to investigate the possibility of using reprocessed irradiated polymeric material. Dielectric relaxation of a radiation modified high impact polystyrene (PS-HI) has been investigated by the time dependence of charging and discharging current. The transient currents for their radiated PS-HI were well approximated by the power function of the logarithm of time and related to the fractal dimension. It was also shown that yield strength and tensile strength increase while elongation at break decreases with increasing absorbed dose. The specimen prepared by a post-irradiation moulding gave higher melt flow rate than those of specimen formed before irradiation. These results indicate that after radiation the system of PS-HI is reprocessable. It is concluded that an oxygen environment at the beginning of irradiation leads to enhanced chain scission at the expense of crosslinks via peroxide formation and causes oxidative degradation of the main polymer chain of irradiated PS-HI at alow absorbed dose. However, at higher absorbed doses the quasi-inert environment has been established and crosslinking, due to recombination of macroradicals, is dominant.

charging–discharging current; fractal; high impact polystyrene; ionisation gamma-radiation; tensile properties

Rad je prezentiran na skupu Proceedings of the 12th Tihany Symposium on Radiation Chemistry, održanom od 27.08.-01.09.2011.g., Zalakaros, Mađarska ; Ágnes Sáfrány, András Kovács (ur.).